Not too long ago, a friendly 55-year-old woman named Sonda Bruce, who knows just about everybody in Chase County, Kansas, brought together townfolk and visitors alike at Emma Chase's Café in the county seat, Cottonwood Falls. The occasion was an evening of down-home music, in which people play everything from the fiddle to the washboard to the tin whistle.

Prior to the event, Ms. Bruce sent out an invitation that read, in part:

"As a special favor to me - since I'm soooooooo allergic to all forms of chemicals - I'm going to ask you to please leave OFF YOUR PERFUME AND AFTERSHAVE AND SCENTS FOR THE EVENING so I can have a fun evening and not be sick. Thank you!!"

All 40 people or so who showed up respected her wishes, and a good time was had by all. But the careful precautions put into focus what Sonda Bruce's life is like. "Whenever I'm around chemicals, I can force myself and push myself to continue, maybe, through that day with a migraine headache, the swelling up, my kidneys quitting to work. But then I may be down for, like, two or three days. The hardest thing is church, because Sunday morning, everybody puts on all the perfume, all the colognes, all of those types of things. And so I can't go to church," she explaines

Most everyone gets annoyed if someone walks into a crowded space wearing too much cologne. And no one likes to get behind a smelly bus in traffic or pass a farm field that's just been treated with fertilizer.

But for Sonda Bruce and uncounted thousands of other people around the world who suffer from what's called "chemical sensitivity syndrome," it's a whole lot more than annoying.

Such encounters dramatically altered her life, beginning nearly 20 years ago when Ms. Bruce, who is only one meter, 73 centimeters tall, got sick when she came into contact with smokers, laundry detergents - even somebody using cleanser to wipe off tables at a restaurant. Ms. Bruce dropped to less than 36 kilos and would, as she put it, "puff up like a toad." She went to one doctor after another.

"They would send you to another group, to another group, to another group. They just said, basically, 'Go home and prepare to die, 'cause there isn't anything else that we can do for you.'"

Sonda Bruce said she thinks her sensitivity began as a girl on a farm, where she was exposed to strong doses of pesticides and fertilizers. Later, day after day as a hairdresser and then a cosmetologist, she wore and demonstrated products with high chemical concentrations. "If someone would have told me when I was doing chemicals and doing all those hair colors and doing all those shows and so forth, 'You're destroying your health, and this is why,' I would have laughed at them," Ms. Bruce said.

Sonda Bruce's condition went far beyond common allergies to cats or tree pollen or dust.

Her overwhelming and potentially deadly reactions to chemicals included vomiting and diarrhea - symptoms that even the strongest allergy shots did not relieve. Some doctors suggested she wear little paper masks like spray painters use. But chemicals seep into the body through the skin as well as the nose. And Ms. Bruce knew that if she wore the mask around town, people would call her weird or worse.

So she and her husband Gary radically changed their habits. They eliminated meat, processed foods, makeup and of course, colognes. They run water and air purifiers at home, and they have added heavy doses of vitamins and minerals to their diet.

"It's really hard to find doctors that don't think you're a wacko and tell you, 'It's all in your head.' And that's what I went through, going through many, many, many doctors who just said, 'Oh, it's all in your head.' Or, 'It's probably a female problem.' That's always what they blame it on: a 'female problem.' There are so many who just don't get it," she said.

Indeed many physicians are suspicious that this "chemical sensitivity syndrome" is a real medical condition. The world-renowned Mayo Clinic in Rochester, Minnesota, for instance, gets hundreds of referrals a year of patients with severe symptoms that seem far out of proportion to their cause. So much so that the clinic concluded many patients had no organic problem but were simply showing an exaggerated response to distasteful smells. The Mayo Clinic even published a scientific paper recommending that the name of the syndrome be changed from chemical sensitivity to "odor aversion."

Retired Mayo Clinic internist Melvin Amundsen saw hundreds of patients with miseries they said were triggered by one or more odors. "There wouldn't be any abnormal blood test or x-ray or clinical finding that would explain the symptom. The successful treatment was performed in our Department of Psychiatry and Psychology - the cause being mental, psychiatric - or psychogenic - not some organic disease that's happening," Dr. Amundsen said.

The clinic prescribes behavior modification therapy designed to de-sensitize patients' reactions to perfume or smoke or other odors. Along with strong verbal reinforcement, they are slowly exposed to increasing doses of the odors that trigger their symptoms. But many other physicians argue there's much more at work than just a violent dislike of unpleasant smells. Dr. George Miller, a obstetrician and gynecologist in Lewisburg, Pennsylvania, for instance, said research has found a breakdown in the body's immune system in some patients.

Dr. Miller, whose son suffered from chemical sensitivity, disagrees with the Mayo Clinic strategy of gradual de-sensitization toward offensive chemicals. "Now if someone's allergic to penicillin, can we give 'em just a small amount of penicillin? No, because they're going to react to it. So if you have a long, low-level exposure to a chemical, it can cause, over time, a sensitization to that chemical. So they get a headache, or they get chest pains, or they get blurred vision, or they get a belly-ache, or they get joint pains. It just depends upon what that particular person's system does with that particular chemical," Dr. Miller said.

Dr. Miller admits that he's treated hypochondriacs who over-react to normal stimuli around them. He's even seen people fake chemical sensitivity syndrome in hopes of getting disability insurance. But he says most patients with such complaints are genuinely sick.

Dr. Miller sometimes prescribes drops of an anti-allergen that can be placed under the tongue in an emergency. They seem to moderate acute chemical sensitivity.

But for many people like Sonda Bruce in Kansas, the strategy of choice is just to avoid harsh chemicals and plan their ventures out into public very, very carefully.